Automatic electric switch



H. AND 0. LUCAS AND H. W. F. IRELAND.

AUTOMATIC ELECTRIC SWITCH.

APPLICATION FILED MAY 25, I921- Patented June 27, 1922.

1-4) Imam/tans HLu/cafi I 0.Lwaws IIIIIII I! UNITED ST'A'EES' PATENT OFFICE.

HARRY LUCAS, OLIVER LUCAS, AND HAROLD WILLIAM FRANK IRELAND, 0F

BIRMINGHAM, ENGLAND.

AUTOMATIC ELECTRIC SWITCH.

Application filed May 26,

T0 oZZ whom it may concern:

Be it known that we, HARRY LUCAS, OLI- VER LUCAS, and HAROLD WILLIAM 'Fniinn IRELAND, residing at Great King Street, in the city of Birmingham, England, sub ects of the King of Great Britain and Ireland, have invented certain new and useful Tinprovements Relating to Automatic Electric Switches, of which the following is a specification.

This invention relates more particularly to the electrical installations of motor vehicles, and has for its object to provide an improved automatic switch which connects the dynamo and battery when a predetermined voltage is attained in the dynamo and disconnects them when the voltage falls below that value. One of the difliculties commonly experienced with apparatus of this kind is that in the event of even momentary sticking of the contacts a heavy reverse current may flow from the battery into the dynamo, and as a reverse current is usually just as effective as a current of normal direction for holdingthe cut-out in action, the occurrence of a heavy reverse current may have serious consequences both to the dynamo and the battery. This defect 1s by our invention avoided in every simple and effective manner.

Referring to the accompanying drawlIl sz- %igure 1 is a diagrammatic sectional view illustrating an automatic switch constructed in accordance with this invention.

Figure 2 is a plan of the switch.

In carrying the invention into effect as shown a flat iron base n carries at right a11- gles to one side three iron members 0, p, q situated parallel with each other. Preferably the base is made from an iron strip with one end bent up at right angles to form one (0) of the aforesaid members, the other two being in the form of cylindrical iron cores screwed or otherwise attached to the base. The middle core ;0 is provided with a series winding 7, and the other core 9 with a shunt winding 0. On the upper end of the middle member is hinged (e. g, by a knife edge 7) an armature in the form of an iron bar 8, which can rock on to either of the end members 0 or g and is normally held in contact with the unwound member 0 by a spring t. Brass stops it are provided on the parts 0 and q to act as abutments for Specification of Letters Patent.

Patented June 2'7, 1922.

1921. Serial No. 472,836.

the part .9. Also the part 3 carries a spring blade 1; fitted with a contact j which can co-operate with a fixed insulated contact 70 carried on the base. To simplify wiring connections, one end of each of the windings is electrically connected to the part 011 which it is mounted.

When the dynamo m is not in service the switch is open and the armature s is held by the spring 26 with one end resting on the unwound member 0 and the contacts j, 7. are open. l/Vhen the dynamo is in action the attainment of sufficient voltage enables the magnetization due to the shunt winding 6 to pull the armature over on to the end member g carrying the shunt winding and thus close the contacts j, 7a. Current can now flow through the series winding 7 to the battery Z. The direction of the flux produced by this winding is the same as that due to the shunt winding, and the pull on the armature is augmented. The circuit for the magnetism is constituted mainly by the two wound cores p, g and the intervening portions of the armature and base. When the dynamo stops, or its speed falls below that necessary to maintain a voltage equal to that of the battery the switch opens under the action of the spring 2?. But if the contacts stick current flows from the battery through the series winding in the reverse direction. The flux due to this winding is now diverted (on account of the opposing magneto motive force of the shunt winding) to the unwound. member 0 and the portions of the base and armature between that member and the core 2 of the series winding. When the reverse current reaches a sufficient value the magnetic pull on the armature (assisted by the spring) which is opposed to that due to the shunt winding causes the armature to rock back to its initial position and open the contacts; reverse current is therefore accompanied by a definite opening action on the armature, other than that due to the spring, which pull increases with the magnitude of the reverse current.

Switches as above described are very simple and robust, are capable of being manufactured at small cost and possess all the required reliability in action. 7

Having thus described our invention what we claim as new and desire to secure by Letters Patent is 1. In automatic electric switches, the combination comprising an iron base, three iron members arranged extending from one side of the base, an armature pivoted on the intermediate member, a series Winding on the intermediate member and a shunt Winding on one of the end members, fixed and mor able contacts carried on the base and arrnaturc respectively at the end adjacent to the said shunt Winding, and a spring acting in the direction for holding the contacts apart, substantially as described.

2. In automatic electric switches, the combina ;ion comprising an iron base, three iron members extending from one side 0'? the base, an armature pivoted on the intermeliate member, a series winding on the intermediate member, a shunt winding on one of the end members, a fixed contact on the base, a spring blade on the armature, a Contact on the said blade for coacting with the l ned contact, and a spring actingon the arr ature in the direction for holding the contacts apart, the said contacts being arranged at the end of the switch adjacent to the shunt Winding, substantially as described.

3. In automatic electric switches, the combination comprising an iron base, an end member produced by bending up one end of the base, a pair of core pieces on the base parallel with each other and the said end member, an armature pivoted on the core adjacent to the said end member, and. capable 0t rocking in either direction relatively to the core, a series winding on said core, a shunt winding on the other core, one end of each' Winding being electrically connected to its core, a fixed insulated contact on the base, a blade on the armature, a contact carried by said blade for enacting with the fitted contact, and a spring; acting on the armature in the direction for separatii'lg the contacts, the said contacts being; arranged at the end oi the switch adjacent to the shunt Winding, substantially as described,

In testimony Whereo'l we have signed our names to this specification, 

